This invention relates to the field of optical devices incorporating a plurality of annular reflective baffles therein which prevent off axis rays from reaching a focal plane of the optical device.
Incoming light entering a telescope from a direction that is not parallel to the optical axis of the telescope can degrade the quality of the desired image if the off axis light is not intercepted. Reflective baffles positioned within the bore of the telescope are disclosed in U.S. Pat. No. 3,488,103 issued to Davis, who teaches the use of a reflecting baffle having concave, elliptical surfaces facing the direction that such off axis rays enter the optical device. In order for the disclosed device to exclude off axis radiation to a sufficient extent, the field of view must be substantially reduced. See also U.S. Pat. No. 4,217,026 issued to Radovich. A number of other prior art devices of this type are discussed in U.S. Pat. No.4,542,963 issued to Linlor, and incorporated by reference herein. Other prior art devices employ baffles in which a substantial portion of light rays are trapped and converted to heat which is undesirable.